The release of drugs from an implanted medical device has been shown to be beneficial for the function of devices and the treatment of various medical conditions. For example, delivery of a drug from the device surface can prevent cellular responses initiated by the presence of the implantable device. Also, drug released from the device can prevent conditions that would otherwise shorten the functional life of the device following implantation. Drug released from the device may also be directed at treating a diseased area of the body such at a target tissue.
However, the transfer of drugs from a medical device to a target tissue can be challenging. For example, in some systems elution of a drug from a polymer matrix may not be sufficient to provide a therapeutic amount of the drug to the target tissue. In some systems drug may be released at or move to a site other than the target tissue. Further, many of the drug delivery coating are made for devices with “static surfaces”, that is, surfaces that do not increase in area. Typically, polymer systems that form durable coatings are suitable for these static surfaces. However, on surfaces that are non-static (e.g., elastic surfaces) such durable coatings may not always be appropriate.